1. Field of the Invention
The invention relates to an improved magnet valve, and more particularly to such valves especially for tank venting in motor vehicles.
2. Description of the Prior Art
Magnetic valves for venting vehicles tanks are known and disclosed for instance by German Patent Disclosures DE 42 44 113 A1, DE 196 11 886 A1, and DE 198 52 980.5. In such valves, the magnet core is axially displaced in the magnet housing for adjustment purposes by being screwed into the thread. Such an adjustment is disclosed for instance by U.S. Pat. No. 5,424,704 as well, but in that case the magnet core is screwed into the plastic coil carrier.
In order after the adjustment to provide an anti-rotation element, it is known to apply plastic layers, such as Tuflok or an adhesive, to the thread. Furthermore, anti-rotation elements by later welding or by calking of the two threads to one another are also known.
Such anti-rotation elements require additional method steps for producing the magnet core and therefore entail additional cost. Furthermore, severely fluctuating loosening torques caused by tolerance fluctuations of the magnet core and of the cup-shaped magnet housing as well as of the plastic, in particular Tuflok or adhesive, layer are problematic.
Finally, an anti-rotation element of this kind is also vulnerable to temperature fluctuations and vibrational stresses.
An object the present invention is to provide a magnet valve of this generic type which, in a simple way, enables adjustment with maximum invulnerability to temperature fluctuations and vibrational stresses as well as tolerance fluctuations between the magnet core and the magnet housing, and to prevent relative rotation of the magnet core.
The further male-threaded portion on the hollow-cylindrical magnet core advantageously forms its own thread course in the coil carrier without metal-cutting machining and presses itself in, in a manner fixed against relative rotation, thus in a simple way attaining an optimal anti-rotation element, and because the adhesive or plastic layers known from the prior art are dispensed with, the tolerances of only two components now have to be taken into account for the anti-rotation element, and these can be made more secure in process terms with a view to production. Furthermore, an anti-rotation element of this kind has loosening torques that can be readily adjusted. Furthermore, this arrangement has substantially higher strength than a thin layer of plastic or adhesive that is employed in anti-rotation elements known from the prior art. The precision of adjustment is preserved because the magnet core is screwed into the metal magnet housing.